Cheat Codes Using stones: Use stones and place them at sensors to keep doors open and elevators in position. Throw a stone to distract aliens, and to allow enough room to kill them. Throwing a stone triggers some laser sensors, killing the aliens easily. Using the Tele Receiver and Transmitter: There is only one time that the Tele Receiver and the Tele Transmitter must be used, which is very shortly they are found. Use them later to speed up game time by avoiding the need to run back a long distance.